A voluntary asso



A. PELLOW.

LENS FORMING PROCESS.

APPLICATION FILED JAN. 2, 1918.

1 12,920. Patented Aug. 12,- 1919.

ATTORNEYS .and described within tin'rrnn sra rns PATENT ARTHUR IPELLOVV', OF SOUTI-IBBIDGE, MASSACHUSETTS, ASSIGNOR TO AMERICAN OPTICAL COMPANY, 013 SOUTHBRIDGE, MASSAIJHUSFLT.'IS;v A VOLUNTARY ASSO- GIATION OF MASSACHUSETTS.

LENS-FOBJIIING PROCESS.

Specification of Letters Patent.

Patented Aug. 12. 19119.

To all whom it may concern:

Be it known that I, ARTHUR PnLLoW, of Southbridge, in the county of lVorcester and State of Massachusetts, have invented certain new and useful. Improvements in Lens-Forming Processes, of which the following is a specification.

This invention relates to improvements in processes of forming lenses and has particular reference to a novel and improved process of forming what is commonly known as a fused bifocal lens.

One of the leading' objects of the present invention is the provision of novel and improved process of forming fused bifocal lenses which shall entirely eliminate the necessity for metal glass or other spacing members for holding the two parts of the lens in spaced relation as they are submitted to the fusing temperature.

A further object of the present invention is the provision ofan improved construction of button or segment member for attachment to a suitably prepared major lens blank. which button shall be so formed and prepared with respect to the major blank as to automatically space itself therefrom and allow but gradual contact between the joiningfaces of the two parts as they are subjected to feeding temperature.

Other objects and advantages of my improved process and structure for carrying the same into eiiiect should be readily understood by reference to the following specification taken in connection with the accompanying drawings, and it will be under-' stood that I' may make any modifications in the specificdetailsot construction shown the scope of the appended claims without departing-\t'rom of exceeding the spirit of my invention.'\

.FlgllIB I respresentsi i plan View or" the.

major blank.

Fig. II represents a -similar View of the bifocal button. A

Fig. V represents a view similar to Fig. III showing the article after fusion.

Fig. VI is a similar view takenat right angles to Fig. V.

In the drawings. the numeral 1 designates the usual major crown glass blank such as ordiarily used in the formation of fused bifocals, having formed therein the spherical depression or countersink 2 adapted to receive and have. united therewith the flint segment or button 3, the bifocal addition as is well known being secured through the differenee in index of refraction of the crown and flint glasses. and the exposed faces of the button and adj acent major blank being preferably subsequently ground oil in a single continuous curve, this subsequent process, however, not entering into the essentials of my present invention.

Hitherto in the formation of lenses of this character it has been deemed necessary to hold the segment and major blank in spaced relation one to the other at one or more points, either by the interposition of a glass, metal or other wedge between the parts, by the formation of knobs or bosses on the major blank engaging the segment to hold it in raised position, or by the use of means at the side of the major blank engaging a portion of the segment.

It is the purpose of my present invention 3 to do away with all these spacing members and to so construct the parts that they will initially satisfactorily space themselves.

In the 'accomplishment of this result. as should be clearly understood by reference to FigsIII and IV, I grind the button 3.

with a toi-ic in place of a spherical curve but intended to eventually be fused. in to a spherical countersink in the main blank.

For example, let it be supposed that the curve of the countersink shown in Figs. III and IV is that of (5-7. sphere; the curve of the segment illustrated in Fig. III might then for example, be a. slightly weaker con- Fig. III represents a transverse section tnageneric'curve, such as a+6. so that when with the parts 1n position for fusion.

Fig. IV representsiya sectional View at i right gles to Fig. IIII the segment'is placed on the major blank 'in the meridian of the +6. curve it will touch at thd edges butthe center portion will from the bottom of the same, While the curve on the hiu'teu in this meridian \Vtli i he coutraeeuenc to that ot the countercenter,

ho s prereuted ou account oil? the it in. 1 ii'ieridiau, so that shown c will entirety major iJltlli-I in the .r i save used the i; +8. for purposes 0 'on only, ca he countersink m ed with any desi 'ed curve, as

1 the toric surfaces 0" the segment, and re found by experiment that sat11sifacouh a quarter diopter variation between the curves ot the countersink and segment in place of the tall diopter here mentioned.

In any event, the essential result is the same, ii, that as the parts are subjected to a fusing;- heat; the segment l sing of glass having a lower softening point than the mac-r hianl i will .;often as an entirety and on account, (f the center Weight of the glass and the fact that it supported at the ends only will drop down from the Weaker, or in the present case, the +6 curve to fit the slightly stronger or '7. curve, when there will then be a line or". contactalong the section of Fig. HI, the production of this line of conttjt being. as before stated, due both to the. Weight of material at the center. with the end supports, and to the fact that at right angles to the line of Ill the segment on account of this stronger curve curves up a Way from the couute sink. After the lens has thus settl d down in 0 its line of contact which stcasdies the segment, t'urthcr heating action will continue the soteniug of the segment to such extent that its edges will then roll downward from the +8. to lit the 7. curve this gradual dropping down of the edges in its rolling action from the center point, serving to force out the air from the two glasses. preventing the formation of bubbles and allowing the two, surfaces to properly uuite. I

To best bring out the effect produced in Fig. V the upper surface of the segment is shown concavcd to bring: out the elt'ect. of dropping ol' the structure shown in Figv ill. while in Fig. Vi. the segment is shown as slightly coiirexed to bring out the cll'eet of rolling down o'l with to a he:

the edges into contact major blank in the opposite it will be understood, however, final etlcet produced on the outer the seguiei'it is unimportz'at in this iureutiou since the upper face will be 1 1d away, for example, substantially the dotted lines shown in Figs. V and during the formation of the completed lens.

1 claim:

1. The process of forming a fused. bifocal lens, consisting in foru'iiug a major blank and segn'ient with contrageuerie surfaces, one oilf ultl surfaces being spheri ad and the other wing toric, superimposing the parts to bring; the surf: ces in substantial Contact one ritl t lie other, and subjecting: the parts sulticicnt to cause one of the mem- .b to assuu'ie the shape of and unite with otter.

ie process of forming a fused bitcal consisting in forming a major blank 'uk, formlug a segment, "with a convex torn. surface, superimposing the segment on the eouutersuulr; portion ot the major lens, Whereh surface contactbetween the parts is prevented on account ol the difference in curves of the segment in its two meridians, and subjecting the parts to a 'l'usiue heat to cause the segment to assume the curve of the countersink and firmly unite therewith.

The process of forming a fused bifocal lens, consisting in forming a major blank with a spherical countersinkand a segment with a contrageueri-c toric surface one of "whose curres is greater than and the other of whose curves is less than that ofth" countersink, placing the segment; above the countersink and in contact with the major blank, and subjecting the parts to heating action to soften the segment, till its curves will tit and corrcsprmd. to the spherical curve of the coiuitersink.

1-. The process of forming a fused. bifocal lens consisting: iii forming a major portion with. a countersink and forming a segment with a toric face. one of the curves on the toric face being a stronger curve than the curve of the countersink or the curve in the meridian at right angles thereto on the segment, whereby as the blank is softened there will first be a line of contact between the segment and the countersink and the segment Will sulisequoutl roll down. at both sides from the line of Contact from the center outward "n the final uniting of the parts.

The process of forming a lens of the charactm described. consisting in forming a major blank with a countersink and upwith a concave spherical couulie plying; tlereto a segment, i'iaviug a toric uniting lace, its curve in at least one meridian differing from that of the counter Intestimony whereof I have afiixed my sink to wlfiiich it is applied, wlz1ereby1 tille signature, in presence of two witnesses. parts will rst join in a line contact an t e 7 segment will subsequently roll out to assume ARTHUR, FELLOW the curvature of the countersink forcing. Witnesses: all air bubbles-out in advance of Contact be- E. COLEMAN- Ween the parts. A. S. CONN. 

